Diablo — Plant Summary
- EIA Plant ID
- 6432
- Capacity
- 182.4 MW
- Primary Fuel
- Hydro
- Technology
- Conventional Hydroelectric
- Status
- Operating
- Location
- Whatcom, WA
- Operating Since
- 1936
- Generators
- 4
- Operator
- City of Seattle - (WA)
- Parent Company
- —
- Annual Generation
- 361,708 MWh
- Capacity Factor
- 22.6%
- Balancing Authority
- Seattle City Light
- ISO/RTO
- —
- NERC Region
- WECC
Diablo
OperatingHydro
Ranked #17 of 75 Hydro plants in WA#101 of 1454 nationally
182.4 MW Hydro operating in Whatcom, WA — Seattle City Light
EIAGEMWD
182.4 MW
Nameplate Capacity
4
Generators
units
Conventional Hydroelectric
Technology
1936
Operating Since
Location
Ownership & Operator
Owner data does not fully agree across sources.
EIA typically reports the operating utility, while GEM resolves to the financial owner or parent corporation. Both can be correct.
| Field | EIA | GEM | Wikidata |
|---|---|---|---|
| Operator | City of Seattle - (WA) | Seattle City Light | — |
| Owner(s) | City of Seattle - (WA) | Seattle City Light [100%] | — |
| Status | Operating | operating | — |
Ownership Chain
GEM identifies the owner as Seattle City Light [100%]
This entity is not yet in the GEM ownership database — chain unavailable.
About
Diablo Dam is one of three dams along the upper Skagit River in Whatcom County, Washington and part of the Skagit River Hydroelectric Project that supplies Seattle with some of its power needs. The dam was built in Diablo Canyon, a gorge of solid granite with vertical walls rising 160 feet (49 m) from the river bed, yet were less than 100 feet (30 m) apart. Construction began in 1927, and was completed in 1930. The dam began generating electricity in 1936. The town of Diablo was established to house the workers building the dam.
Read more on WikipediaThe Diablo hydroelectric plant, identified by plant ID 6432, is located in Whatcom County, Washington. The plant has a total capacity of 182.4 MW across four generators, utilizing conventional hydroelectric technology and water as its primary fuel source. It began operating in 1936 and is owned and operated by the City of Seattle - (WA). Diablo operates within the Seattle City Light balancing authority and the Western Electricity Coordinating Council (WECC) NERC region.
Diablo's latest annual generation was 361,708 MWh, resulting in a capacity factor of 22.6%. The plant is ranked as the 17th largest in Washington out of 23 plants and 101st nationally out of 194 plants. News coverage related to the plant includes 5 articles categorized as regulatory, 4 as industry-related, and 1 pertaining to the grid.
Generated from EIA, GEM, and public data sources
Engineering & Generators
Grid Context
NERC Region
WECC
Balancing Authority
Seattle City Light
Grid Voltage
230 kV
Regulatory Status
RE
Entity Type
Municipal
Sector
Electric Utility
Generation
13.5K MWh
Latest Month
361.7K MWh
Annual Generation
22.6%
Capacity Factor
Jan 2022 – Dec 2024
Financial Data
No financial data available for this plant.
Pricing & Market Data
Market Position
LMP Node
DIABLO_2_GEN31GNODE
Pricing Hub
—
News & Articles (10)Beta
Last updated 2026-03-26
View all 10 articles